It really sounds as if your bobbin tension is too tight. Did you adjust that, or do you have one of those machines where you're "not supposed to". If so, it can and should be done, and I can tell you how to do it. Just PM me.

Did you think of using invisible thread in the bobbin (make sure you use the right needle for invisible)? Don't know if that works for quilting or if it works in the bobbin but might be worth a try. I have never used invisible thread but I was told you have to have the right kind of needle for invisible (can't remember if it is a metallic needle or not). I'm sure someone here will know, for sure.

I'm a longarmer and this is just the nature of the beast.Maybe you could use "So Fine" or "Bottom Line"in the bobbin.These are bobbin threds that I have been useing for quite sometime.But dots on the back are virtually impossible to avoid.In a perfect world the threads would meet in the middle of the quilt sandwich and be perfactely[?] balanced.But no matter what the books tell you,that isn't possible.Are you using a domestic machine to quilt this,or do you have a mid arm or longarm machine?

I thought I was the only one who used Sharpies for that !! I repaired a tear in a friend's quilt (a lonestar!!) that she had damaged by putting a suitcase onto the bed. The slice was about an inch long in a Forest Green diamond. After slipping the fusible web into the hole and fusing it in place, there were still white threads showing from where it tore. Sharpie to the rescue. And you'd be hardpressed to find it!